Technical Field
The present disclosure relates to gate stacks, and more particularly, to replacement gate stacks for p-type field-effect transistors and n-type field effect transistors and methods of forming the same.
Related Art
During integrated circuit fabrication, transistors can be formed in a semiconductor substrate. Each transistor includes a gate through which a current can be passed to change the between source and drain terminals of the transistor. One approach to forming gates includes replacement metal gate (RMG) processing. RMG processing includes generating a number of sacrificial or dummy gates over a structure, such as a fin for a fin field effect transistor (FINFET), so that other processing steps, such as adjacent contact creation, can be carried out without damaging the gate. Once the other processing is carried out, the dummy gates are replaced with a metal to create the final metal gate structure. One challenge associated with RMG processing is reducing total gate resistance in a complementary metal-oxide-semiconductor (CMOS) formed by a p-type field-effect transistor and by a n-type field-effect transistor without affecting work function of the gate stack metals used to form the gate stacks.